TWI787294B - Slurry Composition - Google Patents

Abstract

In one aspect, the present invention provides a polishing liquid composition that can increase the polishing speed and reduce the short-wavelength fluctuation after polishing. In one aspect, the present invention relates to a polishing liquid composition for rough polishing of a Ni-P plated aluminum alloy substrate, which contains non-spherical silica particles, a water-soluble polymer and an aqueous medium, and the above-mentioned The surface tension of a 1% by mass aqueous solution of a water-soluble polymer at 25°C and pH 1.5 is 52 mN/m or more and 71 mN/m or less.

Description

Slurry Composition

The invention relates to a polishing liquid composition for rough grinding of a Ni-P plated aluminum alloy substrate, a manufacturing method of a magnetic disk substrate, and a polishing method of the substrate.

In recent years, the miniaturization and increase in capacity of magnetic disk drives have progressed, and higher recording densities are required. Therefore, it is necessary to improve the detection sensitivity of high recording density magnetic signals, and the industry is promoting the development of technologies to further reduce the flying height of the magnetic head and reduce the unit recording area. For magnetic disk substrates, in order to cope with the low lift of the magnetic head and ensure the recording area, it is strictly required to improve the smoothness and flatness (reduction of surface roughness, waviness, and end face collapse) or to reduce surface defects (residual abrasive grains, reduction of scratches, protrusions, pits, etc.).

In response to such requirements, from the viewpoint of improving surface quality such as smoother and less damage and improving productivity, in the production method of hard disk substrates, multi-stage polishing with more than two stages of polishing steps is often used Way. Generally, in the final grinding step of the multi-stage grinding method, that is, the fine grinding step, in order to meet the requirements of reducing surface roughness and reducing damage such as scratches, protrusions, and pits, the final processing grinding containing colloidal silica particles is used As for the liquid composition, a polishing liquid composition containing alumina particles is used in a polishing step earlier than a fine polishing step (also called a rough polishing step) from the viewpoint of improving productivity. However, in the case of using alumina particles as abrasive grains, there are cases where dielectric defects are caused by texture scratches generated by the alumina particles piercing the substrate.

Therefore, the industry proposes a polishing liquid composition that does not contain alumina particles and contains silica particles as abrasive grains (for example, Patent Documents 1-3). Prior Art Documents Patent Documents

Patent Document 1: Japanese Patent Laid-Open No. 2013-229098 Patent Document 2: WO2015/146942 Patent Document 3: WO2017/051770

[Problem to be solved by the invention]

With the increase in capacity of magnetic disk drives, the requirements for the quality of the substrate surface have become more stringent, and it is required to improve the smoothness and flatness of the substrate surface. Furthermore, in the rough polishing using the conventional polishing liquid composition, it is expected to further reduce the short-wavelength fluctuation of the polished substrate surface.

Therefore, in one aspect, the present invention provides a polishing liquid composition for rough polishing of a Ni-P plated aluminum alloy substrate, which can increase the polishing speed and reduce short-wavelength fluctuations on the surface of the polished substrate. [Technical means to solve the problem]

In one aspect, the present invention relates to a polishing liquid composition for rough polishing of a Ni-P plated aluminum alloy substrate, which contains non-spherical silica particles, a water-soluble polymer and an aqueous medium, and the above-mentioned The surface tension of a 1% by mass aqueous solution of a water-soluble polymer at 25°C and pH 1.5 is 52 mN/m or more and 71 mN/m or less.

In another aspect, the present invention relates to a method for manufacturing a magnetic disk substrate, which includes a polishing step of using the polishing liquid composition of the present invention to polish an aluminum alloy substrate coated with Ni-P.

In another aspect, the present invention relates to a method for polishing a substrate, which includes a polishing step of using the polishing liquid composition of the present invention to polish a Ni-P plated aluminum alloy substrate. [Effect of Invention]

According to the polishing liquid composition of the present invention, the effect of increasing the polishing speed and reducing the short-wavelength fluctuation after polishing can be exerted.

The present invention is based on the insight that by using a polishing liquid composition containing non-spherical silicon dioxide particles and a water-soluble polymer with a specific surface tension for rough grinding of an aluminum alloy substrate plated with Ni-P, it is possible to Increase the grinding speed to reduce short-wavelength fluctuations after grinding.

That is, the present invention relates to a polishing liquid composition (hereinafter also referred to as "the polishing liquid composition of the present invention") for rough polishing of a Ni-P plated aluminum alloy substrate, which contains non- Spherical silica particles, water-soluble polymers, and water-based media, and the surface tension of a 1% by mass aqueous solution of the above-mentioned water-soluble polymers at 25°C and pH 1.5 is not less than 52 mN/m and not more than 71 mN/m.

The mechanism by which the effect of the present invention is expressed is not clear, but it is presumed to be as follows. The substrate to be polished is usually polished by clamping the substrate to be polished by a platen attached with a polishing pad, supplying the polishing liquid composition to the grinder, moving the platen or the substrate to be polished, and grinding the substrate to be polished. Grind. During such polishing, if a water film is formed between the polished substrate and the polishing pad, hydroplaning may occur. If water drift occurs, the force from the polishing pad will not be sufficiently transmitted to the abrasive particles or the surface of the substrate, and the polishing speed will decrease, resulting in uneven polishing and short-wavelength fluctuations. Therefore, the polishing liquid composition of the present invention contains non-spherical silica particles and a water-soluble polymer with specific surface tension. It is considered that the aqueous medium in the polishing liquid composition penetrates into the polishing pad, the thickness of the water film appearing between the substrate to be polished and the polishing pad becomes thinner, and the water drifting phenomenon is suppressed. It is also considered that, as a result, the polishing rate is increased and the occurrence of short-wavelength fluctuations is suppressed. However, the present invention may not be limitedly interpreted by these mechanisms.

In the present invention, the "waviness" of the substrate refers to irregularities on the surface of the substrate having a longer wavelength than the roughness. In the present invention, "short-wavelength fluctuation" means, for example, fluctuation observed at a wavelength of 80 to 500 μm. By reducing the short-wavelength fluctuation of the polished substrate surface, the flying height of the magnetic head can be reduced in the magnetic disk drive, and the recording density of the magnetic disk can be increased. The short-wavelength fluctuation of the substrate surface can be measured by the method described in the examples.

[Non-spherical silica particles] The polishing liquid composition of the present invention contains non-spherical silica particles (hereinafter also referred to as "particle A1") as abrasive grains. Examples of the particle A1 include colloidal silica, precipitated silica, fumed silica, and surface-modified silica. From the viewpoint of securing the polishing rate and reducing short-wavelength fluctuations, the particle A1 is preferably colloidal silica, more preferably colloidal silica having a specific shape satisfying the following parameters. As the usage form of the particle A1, a slurry form is preferable.

The average sphericity of the particles A1 is preferably at least 0.55, more preferably at least 0.60, from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuations, and from the same viewpoint, is preferably at most 0.85, more preferably 0.80 or less, more preferably 0.75 or less. More specifically, the average sphericity of the particles A1 is preferably not less than 0.55 and not more than 0.85, more preferably not less than 0.60 and not more than 0.80, still more preferably not less than 0.60 and not more than 0.75. In the present invention, the average sphericity of particle A1 is the average value of the sphericity of at least 200 particles A1. The sphericity of the particle A1 can be calculated by using, for example, the projected area S and the projected perimeter L of the particle A1 using TEM observation and image analysis software, etc., and calculated according to the following formula. Sphericity=4π×S/L ² The sphericity of each particle A1 is the same as the above-mentioned average sphericity, preferably 0.55 or more, more preferably 0.60 or more, and preferably 0.85 or less, more preferably 0.80 or less, and still more preferably 0.75 or less. More specifically, the sphericity of each particle A1 is preferably not less than 0.55 and not more than 0.85, more preferably not less than 0.60 and not more than 0.80, still more preferably not less than 0.60 and not more than 0.75.

The average minor diameter of the particles A1 is preferably 160 nm or more, more preferably 180 nm or more, and further preferably 185 nm or more from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuations, and from the same viewpoint, Preferably it is 500 nm or less, more preferably 450 nm or less, and still more preferably 400 nm or less. More specifically, the average short axis of the particles A1 is preferably from 160 nm to 500 nm, more preferably from 180 nm to 450 nm, still more preferably from 185 nm to 400 nm. In the present invention, the average short diameter of the particles A1 is the average value of the short diameters of at least 200 particles A1. The short axis of the particle A1 is, for example, the length of the short side of the rectangle when the smallest rectangle circumscribing the projected image of the particle A1 is drawn using, for example, TEM observation and image analysis software. Similarly, the long diameter of the particle A1 is the length of the long side of the above-mentioned rectangle.

The average aspect ratio of the particles A1 is preferably at least 1.10, more preferably at least 1.15, and still more preferably at least 1.20 from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuations, and from the same viewpoint, it is more preferably 2.00 or less, more preferably 1.70 or less, still more preferably 1.50 or less. More specifically, the average aspect ratio of the particles A1 is preferably from 1.10 to 2.00, more preferably from 1.15 to 1.70, still more preferably from 1.20 to 1.50. In the present invention, the average aspect ratio of the particles A1 is the average value of the aspect ratios of at least 200 particles A1. The aspect ratio of the particle A1 is the ratio of the long diameter to the short diameter of the particle A1 (long diameter/short diameter).

The BET (Brunauer-Emmett-Teller, Buert) specific surface area of the particles A1 is preferably 200 m ² /g or less, more preferably 100 m ² /g or less, from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuations , more preferably 80 m ² /g or less, and from the same viewpoint, preferably 10 m ² /g or more, more preferably 20 m ² /g or more, still more preferably 30 m ² /g or more . More specifically, the BET specific surface area of the particles A1 is preferably from 10 m ² /g to 200 m ² /g, more preferably from 20 m ² /g to 100 m ² /g, still more preferably 30 m 2 /g. m ² /g or more and 80 m ² /g or less. In the present invention, the BET specific surface area can be calculated by the nitrogen adsorption method.

The average primary particle diameter D1 of the particles A1 is preferably at least 50 nm, more preferably at least 60 nm, and further preferably at least 70 nm from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuations. In other words, it is preferably 200 nm or less, more preferably 150 nm or less, and still more preferably 120 nm or less. More specifically, the average primary particle diameter D1 of the particles A1 is preferably not less than 50 nm and not more than 200 nm, more preferably not less than 60 nm and not more than 150 nm, still more preferably not less than 70 nm and not more than 120 nm. In the present invention, the average primary particle diameter D1 of the particles A1 can be calculated using the BET specific surface area, and specifically, can be calculated by the method described in the examples.

The average secondary particle diameter D2 of the particles A1 is preferably at least 50 nm, more preferably at least 60 nm, further preferably at least 100 nm, and even more preferably at least 110 nm from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuations. nm or more, more preferably 140 nm or more, and from the same viewpoint, preferably 500 nm or less, more preferably 400 nm or less, further preferably 300 nm or less, still more preferably 200 nm or less, and further More preferably, it is less than 170 nm. More specifically, the average secondary particle diameter D2 of the particles A1 is preferably not less than 50 nm and not more than 500 nm, more preferably not less than 60 nm and not more than 400 nm, still more preferably not less than 100 nm and not more than 300 nm, and even more preferably It is preferably 110 nm or more and 200 nm or less, and more preferably 140 nm or more and 170 nm or less.

In the present invention, the average secondary particle diameter D2 of the particles A1 refers to the average particle diameter based on the scattering intensity distribution measured by the dynamic light scattering method. In the present invention, the so-called "scattering intensity distribution" refers to the weight conversion of submicron particles obtained by dynamic light scattering (DLS, Dynamic Light Scattering) or quasielastic light scattering (QLS, Quasielastic Light Scattering). Particle size distribution. The average secondary particle diameter D2 of the particles A1 in the present invention can be obtained specifically by the method described in the examples.

The particle diameter ratio (D2/D1) of the average secondary particle diameter D2 of the particles A1 to the average primary particle diameter D1 is preferably 1.50 or more, more preferably 2.00 or more, from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuations. And from the same viewpoint, it is preferably 4.50 or less, more preferably 4.00 or less. More specifically, the above-mentioned particle size ratio (D2/D1) is preferably from 1.50 to 4.50, more preferably from 2.00 to 4.00.

The shape of the particle A1 is preferably a silicon dioxide particle with a smaller particle size than the secondary particle size of the particle A1 as a precursor particle from the viewpoint of ensuring the polishing speed and reducing short-wavelength fluctuations. The shape formed by agglomeration or fusion of matter particles. As the type of particle A1, from the viewpoint of ensuring the polishing speed and reducing short-wavelength fluctuations, it is preferably selected from the group consisting of gold flat sugar-type silicon dioxide particles Aa, special-shaped silicon dioxide particles Ab, and special-shaped gold flat sugar-type silicon dioxide particles. The silicon dioxide particles Ac and at least one type of silicon dioxide particles among the precipitated silicon dioxide Ad are more preferably irregular-shaped silicon dioxide particles Ab and the precipitated silicon dioxide particles Ad. Particle A1 may be one type of non-spherical silica particles, or a combination of two or more types of non-spherical silica particles.

In the present invention, the silicon dioxide particle Aa of Jinpei sugar type (hereinafter also referred to as "particle Aa") refers to a silicon dioxide particle having specific verrucous protrusions on the surface of the spherical particle. The particle Aa is preferably in a shape formed by agglomeration or fusion of the largest precursor particle a1 and one or more precursor particles a2 whose particle diameter is 1/5 or less of the precursor particle a1. The particle Aa is preferably in a state where a part of the plurality of precursor particles a2 with a smaller particle size is buried in one precursor particle a1 with a larger particle size. Particles Aa can be obtained, for example, by the method described in JP-A-2008-137822. The particle diameter of the precursor particle can be obtained as the equivalent circle diameter measured in one precursor particle in an observation image obtained by TEM or the like, that is, the major diameter of a circle having the same area as the projected area of the precursor particle. The particle size of the precursor particles in the irregular-shaped silica particles Ab and the irregular-shaped and Kopeisu-shaped silica particles Ac can also be obtained in the same manner.

In the present invention, the special-shaped silica particle Ab (hereinafter also referred to as "particle Ab") refers to an agglomeration or Silica particles in the shape of fusion (refer to Figure 1). The particle Ab is preferably in a shape formed by agglomeration or fusion of two or more precursor particles whose particle diameter is within 1.5 times the particle diameter of the smallest precursor particle. Particle Ab can be obtained, for example, by the method described in JP-A-2015-86102.

In the present invention, the silicon dioxide particle Ac (hereinafter also referred to as "particle Ac") of irregular shape and gold flat sugar type is the above-mentioned particle Ab as the precursor particle c1, and the largest precursor particle c1 and the particle size are the precursor The shape formed by agglomeration or fusion of one or more precursor particles c2 of less than 1/5 of the particle c1.

As the production method of particle Aa, particle Ab, and particle Ac, for example, water glass method, sol-gel method, and pulverization method can be mentioned, and the water glass method is preferred from the viewpoint of ensuring the grinding speed and reducing short-wavelength fluctuations. . The water glass method refers to the particle growth method using an aqueous solution of silicic acid as the starting material.

In the present invention, the precipitated silica particles Ad (hereinafter also referred to as "particles Ad") refer to silica particles produced by a precipitation method. The shape of the particles Ad is preferably a shape formed by agglomerating a plurality of primary particles, and more preferably a shape formed by agglomerating a plurality of primary particles having relatively large particle diameters, from the viewpoint of securing the polishing speed and reducing short-wavelength fluctuations.

As a method for producing the particles Ad, known methods such as the method described on pages 65 to 69 of Tosoh Research-Technical Report Vol. 45 (2001) can be cited, for example. Specific examples of the method for producing the particles Ad include a precipitation method in which silica particles are precipitated by a neutralization reaction between a silicate such as sodium silicate and an inorganic acid such as sulfuric acid. It is preferable to carry out the above-mentioned neutralization reaction under relatively high temperature and alkaline conditions, whereby the growth of the primary particles of silicon dioxide proceeds rapidly, and the primary particles are aggregated and precipitated in the form of flocs, and it is preferable to further pulverize them, by This yields particles Ad.

Particle A1 preferably contains at least one selected from particles Aa, Ab, Ac, and Ad, more preferably contains at least one selected from particles Ab and particle Ad, from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuations. 1 species. The total amount of particles Aa, Ab, Ac, and Ad in particle A1 is preferably at least 50% by mass, more preferably at least 70% by mass, and still more preferably 80% by mass, from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuations. % by mass or more, more preferably not less than 90% by mass, still more preferably substantially 100% by mass.

The content of particle A1 in the polishing liquid composition of the present invention is preferably at least 0.1% by mass, more preferably at least 0.5% by mass, and still more preferably at least 1% by mass, from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuation or more, more preferably at least 2% by mass, and, from the viewpoint of economic efficiency, preferably at most 30% by mass, more preferably at most 25% by mass, still more preferably at most 20% by mass, and still more preferably at most 15% by mass or less. More specifically, the content of the particles A1 is preferably not less than 0.1% by mass and not more than 30% by mass, more preferably not less than 0.5% by mass and not more than 25% by mass, still more preferably not less than 1% by mass and not more than 20% by mass, Furthermore, it is more preferable that it is 2 mass % or more and 15 mass % or less.

[Other Silica Particles] The polishing liquid composition of the present invention may contain silica particles other than Particle A1 as abrasive grains. The silica particles other than particle A1 are preferably spherical silica particles (hereinafter also referred to as "particle A2") from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuation. As particle A2, colloidal silica, fumed silica, surface-modified silica etc. are mentioned, for example. As particle A2, it can correspond to the colloidal silica normally marketed, for example. Particle A2 may be one kind of spherical silica particles, or may be a combination of two or more kinds of spherical silica particles. The use form of the particle A2 is preferably a slurry form.

The average sphericity of the particles A2 is preferably at least 0.86, more preferably at least 0.88, and is preferably at most 1.00, preferably at most 0.95, from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuation. More specifically, the average sphericity of the particles A2 is preferably not less than 0.86 and not more than 1.00, more preferably not less than 0.88 and not more than 0.95. From the same viewpoint, the sphericity of each particle A2 is preferably within the same range as the average sphericity of the above-mentioned particles A2. The average sphericity and sphericity of particle A2 can be measured by the same method as particle A1.

The average minor diameter of the particles A2 is preferably at least 15 nm, more preferably at least 45 nm, and still more preferably at least 85 nm from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuations, and from the same viewpoint, Preferably it is 200 nm or less, more preferably 150 nm or less, still more preferably 130 nm or less. More specifically, the average short axis of the particles A2 is preferably from 15 nm to 200 nm, more preferably from 45 nm to 150 nm, still more preferably from 85 nm to 130 nm. The average short axis of particle A2 can be calculated by the same method as particle A1.

The average aspect ratio of the particles A2 is preferably at least 1.00, more preferably at most 1.15, more preferably at most 1.10, and still more preferably at most 1.08, from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuation. From the same viewpoint, the aspect ratio of each particle A2 is preferably within the same range as the average aspect ratio of the spherical silica particles. The average aspect ratio and aspect ratio of particle A2 can be calculated by the method similar to particle A1.

The average primary particle diameter D1 of the particles A2 is preferably at least 15 nm, more preferably at least 30 nm, and further preferably at least 40 nm from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuations. In other words, it is preferably 150 nm or less, more preferably 120 nm or less, and still more preferably 100 nm or less. More specifically, the average primary particle diameter D1 of the particles A2 is preferably not less than 15 nm and not more than 150 nm, more preferably not less than 30 nm and not more than 120 nm, still more preferably not less than 40 nm and not more than 100 nm. The average primary particle diameter D1 of particle A2 can be calculated by the same method as particle A1.

The average secondary particle diameter D2 of the particle A2 is preferably smaller than the average secondary particle diameter D2 of the particle A1 from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuation. From the same point of view, the average secondary particle diameter D2 of the particle A2 is preferably at least 20 nm, more preferably at least 45 nm, further preferably at least 85 nm, and is preferably at most 200 nm, more preferably at least 180 nm. nm or less, more preferably 160 nm or less. More specifically, the average secondary particle diameter D2 of the particles A2 is preferably not less than 20 nm and not more than 200 nm, more preferably not less than 45 nm and not more than 180 nm, still more preferably not less than 85 nm and not more than 160 nm. The average secondary particle diameter D2 of particle A2 can be calculated by the method similar to particle A1.

The particle size ratio D2/D1 of the average secondary particle diameter D2 of the particles A2 to the average primary particle diameter D1 is preferably 1.05 or more, more preferably 1.50 or more, and furthermore It is preferably 2.00 or more, and from the same viewpoint, it is preferably 4.00 or less, more preferably 3.50 or less, and still more preferably 3.00 or less. More specifically, the particle diameter ratio D2/D1 is preferably from 1.05 to 4.00, more preferably from 1.50 to 3.50, and still more preferably from 1.50 to 3.00.

Examples of methods for producing the particles A2 include the water glass method, the sol-gel method, and the pulverization method, and the water glass method is preferred from the viewpoint of securing the polishing speed and reducing short-wavelength fluctuations.

When the polishing liquid composition of the present invention contains particles A1 and A2, the content of particle A2 in the polishing liquid composition is more preferably 0.1% by mass or more from the viewpoint of ensuring the polishing speed and reducing short-wavelength fluctuation. Preferably at least 0.5% by mass, and, from the viewpoint of economic efficiency, preferably at most 4.0% by mass, more preferably at most 2.0% by mass, further preferably at most 1.5% by mass, still more preferably at most 1.0% by mass . More specifically, the content of the particles A2 is more preferably from 0.1% by mass to 4.0% by mass, more preferably from 0.1% by mass to 2.0% by mass, still more preferably from 0.1% by mass to 1.5% by mass.

When the polishing liquid composition of the present invention contains particles A1 and A2, the mass ratio (content of particle A1/content of particle A2) of particle A1 and particle A2 in the polishing liquid composition ensures the polishing speed and reduces the short wavelength From the viewpoint of fluctuation, it is preferably 5/95 or more, more preferably 20/80 or more, further preferably 40/60 or more, further preferably 50/50 or more, further preferably 60/40 or more, and further preferably It is preferably 70/30 or more, and from the same viewpoint, it is preferably 95/5 or less, more preferably 90/10 or less, further preferably 80/20 or less, and still more preferably 75/25 or less. More specifically, the above-mentioned mass ratio (content of particle A1/content of particle A2) is preferably 5/95 or more and 95/5 or less, more preferably 20/80 or more and 95/5 or less, and still more preferably 40 /60 or more and 95/5 or less, more preferably 50/50 or more and 95/5 or less, preferably 50/50 or more and 90/10 or less, further preferably 60/40 or more and 90/10 or less, More preferably, it is 70/30 or more and 90/10 or less. When particle A2 is a combination of two or more types of spherical silica particles, the content of particle A2 refers to the total content of these particles. The content of particle A1 is also the same.

When the polishing liquid composition of the present invention contains particles A1 and A2, the average sphericity of the mixed abrasive grains of particles A1 and A2 is preferably 0.55 or more from the viewpoint of ensuring the polishing speed and reducing short-wavelength fluctuations. It is preferably 0.60 or more, and from the same viewpoint, it is preferably 0.85 or less, more preferably 0.80 or less, and still more preferably 0.75 or less. More specifically, the average sphericity of the mixed abrasive grains of particles A1 and A2 is preferably not less than 0.55 and not more than 0.85, more preferably not less than 0.60 and not more than 0.80, still more preferably not less than 0.60 and not more than 0.75. The average sphericity of the mixed abrasive grains can be calculated by the same method as the grain A1.

When the polishing liquid composition of the present invention contains particles A1 and A2, the average primary particle size D1 of the mixed abrasive grains of particles A1 and A2 is preferably 50 nm in terms of ensuring the polishing speed and reducing short-wavelength fluctuations Above, more preferably 60 nm or more, more preferably 70 nm or more, and from the same viewpoint, preferably 200 nm or less, more preferably 150 nm or less, further preferably 120 nm or less. More specifically, the average primary particle diameter D1 of the mixed abrasive grains of particles A1 and A2 is preferably not less than 50 nm and not more than 200 nm, more preferably not less than 60 nm and not more than 150 nm, and still more preferably not less than 70 nm and not more than 120 nm. below nm. The average primary particle diameter D1 of the mixed abrasive grains can be calculated by the same method as the grain A1.

When the polishing liquid composition of the present invention contains particles A1 and A2, the average secondary particle size D2 of the mixed abrasive grains of particles A1 and A2 is preferably 50% in terms of ensuring the polishing speed and reducing short-wavelength fluctuations. nm or more, more preferably 60 nm or more, more preferably 100 nm or more, still more preferably 110 nm or more, still more preferably 140 nm or more, and from the same point of view, preferably 500 nm or less, more preferably Preferably, it is 400 nm or less, more preferably 300 nm or less, still more preferably 200 nm or less, and still more preferably 170 nm or less. More specifically, the average secondary particle diameter D2 of the mixed abrasive grains of particles A1 and A2 is preferably not less than 50 nm and not more than 500 nm, more preferably not less than 60 nm and not more than 400 nm, further preferably not less than 100 nm and not more than 500 nm. 300 nm or less, more preferably 110 nm or more and 200 nm or less, still more preferably 140 nm or more and 170 nm or less. The average secondary particle diameter D2 of the mixed abrasive grains can be calculated by the same method as the grain A1.

When the polishing liquid composition of the present invention contains silicon dioxide particles other than particles A1 and A2, the total content of particle A and particle A2 relative to the whole silicon dioxide particles in the polishing liquid composition ensures the polishing speed and From the viewpoint of reducing short-wavelength fluctuation, it is preferably at least 98.0 mass%, more preferably at least 99.0 mass%, further preferably at least 99.5 mass%, and still more preferably substantially 100 mass%.

[Water-soluble polymer] The surface tension of the water-soluble polymer contained in the polishing liquid composition of the present invention (hereinafter also referred to as "component B") is a 1% by mass aqueous solution of component B at 25°C and pH 1.5. Water-soluble polymers of 52 mN/m or more and 71 mN/m or less. It is considered that the water-based medium in the polishing liquid composition becomes easy to penetrate into the polishing pad due to component B having a surface tension lower than that of water (74 mN/m), thereby increasing the polishing speed and reducing short-wavelength fluctuations. In the present invention, "water solubility" of a water-soluble polymer means having a solubility of 2 g/100 mL or more in water (20° C.).

The surface tension of the 1% by mass aqueous solution of component B at 25°C and pH 1.5 is 52 mN/m or more, preferably more than 55 mN/m, more preferably from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuations 57.5 mN/m or more, and from the same point of view, 71 mN/m or less, preferably 70 mN/m or less, more preferably 69 mN/m or less, still more preferably 65 mN/m or less, More preferably, it is 63 mN/m or less, still more preferably 60 mN/m or less, still more preferably 58 mN/m or less. More specifically, the surface tension of the 1% by mass aqueous solution of component B at 25°C and pH 1.5 is not less than 52 mN/m and not more than 71 mN/m, preferably more than 55 mN/m and not more than 70 mN/m Not more than 55 mN/m and not more than 69 mN/m, more preferably more than 55 mN/m and not more than 65 mN/m, more preferably more than 55 mN/m and not more than 63 mN/m Not more than 55 mN/m and not more than 60 mN/m, more preferably more than 55 mN/m and not more than 58 mN/m, more preferably not less than 57.5 mN/m and not more than 58 mN/m the following. Specifically, the surface tension of component B can be measured by the method described in the examples.

Component B is preferably, for example, a polymer having a hydrophobic group and a hydrophilic group from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuation. As a polymer which has a hydrophobic group and a hydrophilic group, the copolymer containing the structural unit derived from the monomer which has a hydrophobic group and the structural unit derived from the monomer which has a hydrophilic group is mentioned, for example. Examples of monomers having hydrophobic groups include 1-butene, 2-butene, ethylene, propylene, styrene, naphthalene, vinyl monomers having carboxylic acid groups, vinyl monomers having amide groups, etc. . Examples of vinyl monomers having an amide group include methacrylamide, isopropylacrylamide, diethylacrylamide, n-butylacrylamide, second-butylacrylamide, Tributylacrylamide, etc. As a monomer which has a hydrophilic group, the vinyl-type monomer which has a sulfonic acid group, the vinyl-type monomer which has a phosphoric acid group, etc. are mentioned. Among them, as component B, it is more preferable to contain a structure derived from a vinyl monomer having a carboxylic acid group (hereinafter also referred to as "monomer b1") from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuation. unit (hereinafter also referred to as "structural unit b1") and a structural unit (hereinafter also referred to as "structural unit b2") derived from a vinyl monomer having a sulfonic acid group (hereinafter also referred to as "monomer b2") copolymer. It is considered that because the pH value of the polishing liquid composition during use is low (for example, pH value 1~3), the structural unit derived from monomer b1 of component B becomes a hydrophobic group, and the structural unit derived from monomer b2 becomes a hydrophilic group , to promote the penetration of water-based media to the grinding pad, and increase the grinding speed. In this invention, component B can be used 1 type or in mixture of 2 or more types.

<Monomer b1> Monomer b1 is a vinyl monomer having a carboxylic acid group, and is preferably selected from, for example, acrylic acid, methacrylic acid, and maleic acid from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuations. 1 or more of fumaric acid, itaconic acid and their salts, more preferably one or more of them selected from acrylic acid, methacrylic acid, maleic acid and their salts Among the above, more preferably one or two or more selected from acrylic acid, methacrylic acid, and salts thereof. Examples of the salt include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as calcium; ammonium; alkanolamines such as triethanolamine, and the like, and these may be used alone or in combination of two or more.

The content (mass %) of the structural unit b1 in all the structural units of the component B is preferably at least 50 mass %, more preferably at least 60 mass %, and still more preferably It is 70 mass % or more, and from the same viewpoint, it is preferably 95 mass % or less, More preferably, it is 90 mass % or less, More preferably, it is 85 mass % or less. More specifically, the content (mass %) of structural unit b1 in all structural units of component B is preferably 50 mass % or more and 95 mass % or less, more preferably 60 mass % or more and 90 mass % or less, and further preferably Preferably, it is not less than 70% by mass and not more than 85% by mass.

The content (mole %) of the structural unit b1 in all the structural units of the component B is preferably 70 mol% or more, more preferably 80 mol% or more, from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuations, Furthermore, it is preferably 85 mol% or more, and from the same viewpoint, it is preferably 98 mol% or less, more preferably 95 mol% or less, and still more preferably 90 mol% or less. More specifically, the content (mole %) of the structural unit b1 in all the structural units of component B is preferably 70 mol% or more and 98 mol% or less, more preferably 80 mol% or more and 95 mol% % or less, more preferably 85 mol% or more and 90 mol% or less.

<Monomer b2> Monomer b2 is a vinyl monomer having a sulfonic acid group, and is preferably selected from, for example, 2-acrylamide-2-methylpropane from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuation. One or more of sulfonic acid (AMPS), 2-hydroxy-3-(allyloxy)propanesulfonic acid (HAPS), vinylsulfonic acid and their salts, more preferably selected from AMPS, HAPS And one or more of these salts. As the salt, a salt of the above-mentioned monomer b1 can be used.

The content (mass %) of the structural unit b2 in all the structural units of the component B is preferably at least 5 mass %, more preferably at least 10 mass %, and still more preferably It is at least 15% by mass, and from the same viewpoint, it is preferably at most 50% by mass, more preferably at most 40% by mass, and still more preferably at most 30% by mass. More specifically, the content (mass %) of the structural unit b2 in all structural units of the component B is preferably 5 mass % or more and 50 mass % or less, more preferably 10 mass % or more and 40 mass % or less, and further preferably Preferably, it is not less than 15% by mass and not more than 30% by mass.

The content (mole %) of the structural unit b2 in all the structural units of the component B is preferably 2 mol% or more, more preferably 5 mol% or more, from the viewpoint of increasing the polishing rate and improving the short-wavelength fluctuation, Furthermore, it is preferably at least 10 mol%, and from the same viewpoint, it is preferably at most 30 mol%, more preferably at most 20 mol%, and still more preferably at most 15 mol%. More specifically, the content (mole %) of structural unit b2 in all structural units of component B is preferably 2 mol% or more and 30 mol% or less, more preferably 5 mol% or more and 20 mol% % or less, more preferably 10 mol% or more and 15 mol% or less.

The mass ratio (b1/b2) of the structural unit b1 and the structural unit b2 in the component B is preferably 5/95 or more, more preferably 10/90 or more, and further Preferably it is 30/70 or more, more preferably 40/60 or more, still more preferably 50/50 or more, and from the same viewpoint, preferably 95/5 or less, more preferably 90/10 or less, Furthermore, it is more preferably 80/20 or less. From the same viewpoint, the mass ratio (b1/b2) is preferably 5/95 to 95/5, more preferably 50/50 to 90/10.

The molar ratio (b1/b2) of the structural unit b1 and the structural unit b2 in the component B is preferably at least 5/95, more preferably at least 10/90, from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuations, More preferably 30/70 or more, still more preferably 40/60 or more, still more preferably 50/50 or more, still more preferably 60/40 or more, and from the same viewpoint, preferably 95/5 Below, more preferably below 90/10, still more preferably below 85/15, still more preferably below 80/20. More specifically, the above molar ratio (b1/b2) is preferably from 5/95 to 95/5, more preferably from 10/90 to 90/10, still more preferably from 30/70 to 85 /15 or less, more preferably 40/60 or more and 80/20 or less, still more preferably 50/50 or more and 80/20 or less, still more preferably 60/40 or more and 80/20 or less.

The total content (mass %) of structural unit b1 and structural unit b2 in all structural units of component B is preferably at least 80 mass %, more preferably 90 mass %, from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuation or more, more preferably 95% by mass or more, still more preferably 100% by mass.

The total content (mole %) of structural unit b1 and structural unit b2 in all structural units of component B is preferably at least 80 mole %, more preferably 90 mole %, from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuations. Mole % or more, more preferably 95 mole % or more, more preferably 100 mole %.

Component B may further contain other structural units other than the structural unit b1 and the structural unit b2. As other structural units, polyethylene glycol methacrylate, polyethylene glycol acrylate, polyethylene glycol allyl ether, etc. are mentioned, for example.

The arrangement of each structural unit constituting component B may be any of random, block, or graft.

As an embodiment of component B, for example, at least one kind selected from the following copolymers containing structural units derived from (meth)acrylic acid or its salts and 2-acrylamide-2-methylpropane Copolymers of structural units derived from sulfonic acid or its salts, containing structural units derived from (meth)acrylic acid or its salts and structural units derived from 2-hydroxy-3-(allyloxy)propanesulfonic acid or its salts Copolymers, copolymers containing structural units derived from (meth)acrylic acid or its salts and structural units derived from vinylsulfonic acid or its salts. Specific examples of component B include (meth)acrylic acid/2-acrylamide-2-methylpropanesulfonic acid copolymer, (meth)acrylic acid/2-hydroxy-3-(allyloxy ) propanesulfonic acid copolymer, (meth)acrylic acid/vinylsulfonic acid copolymer, etc.

Component B can be obtained, for example, by a known method such as polymerizing a solution containing monomer b1 and monomer b2 by a solution polymerization method. Examples of solvents that can be used for polymerization include: water; aromatic hydrocarbons such as toluene and xylene; alcohols such as ethanol and 2-propanol; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran and diethylene glycol dimethyl ether Ether etc. As a polymerization initiator which can be used for polymerization, a well-known radical initiator is mentioned, for example, ammonium persulfate is mentioned. A chain transfer agent may further be used during polymerization, and examples thereof include thiol-based chain transfer agents such as 2-mercaptoethanol and β-mercaptopropionic acid. In the present invention, the content of each structural unit in all structural units of component B can be regarded as the ratio of the usage amount of each monomer to the total amount of monomers used for polymerization.

The weight average molecular weight of component B is preferably at least 500, more preferably at least 1,000, still more preferably at least 1,500, and from the same viewpoint, it is at most 20,000 from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuation , preferably less than 15,000, more preferably less than 12,000. More specifically, the weight average molecular weight of component B is preferably from 500 to 20,000, more preferably from 1,000 to 15,000, still more preferably from 1,000 to 12,000, still more preferably from 1,500 to 12,000. The weight average molecular weight of component B can be measured by gel permeation chromatography (GPC), specifically, it can be measured by the method described in an Example.

The content of component B in the polishing liquid composition of the present invention is preferably at least 0.001% by mass, more preferably at least 0.005% by mass, and still more preferably at least 0.008% by mass, from the viewpoint of increasing the polishing rate and reducing short-wavelength fluctuations. Above, more preferably at least 0.01% by mass, and from the same viewpoint, preferably at most 1% by mass, more preferably at most 0.5% by mass, still more preferably at most 0.4% by mass, still more preferably at most 0.3% by mass % or less, more preferably 0.2 mass % or less, further preferably 0.1 mass % or less. More specifically, the content of component B is preferably from 0.001% by mass to 1% by mass, more preferably from 0.005% by mass to 0.5% by mass, still more preferably from 0.008% by mass to 0.4% by mass, and furthermore Preferably it is 0.01 mass % or more and 0.3 mass % or less, More preferably, it is 0.01 mass % or more and 0.2 mass % or less, More preferably, it is 0.01 mass % or more and 0.1 mass % or less.

The ratio of the content of component B in the polishing liquid composition of the present invention to the content of particles A1 (mass ratio B/A1) is preferably 0.0005 or more, more preferably from the viewpoint of improving the polishing speed and reducing short-wavelength fluctuations. It is 0.001 or more, more preferably 0.003 or more, and from the same viewpoint, it is preferably 0.085 or less, more preferably 0.020 or less, more preferably 0.015 or less, and still more preferably 0.012 or less. More specifically, the mass ratio B/A1 is preferably from 0.0005 to 0.085, more preferably from 0.001 to 0.020, still more preferably from 0.003 to 0.015, still more preferably from 0.003 to 0.012.

[Aqueous Medium] Examples of the aqueous medium contained in the polishing liquid composition of the present invention include water such as distilled water, ion-exchanged water, pure water, and ultrapure water, or a mixed medium of water and a solvent. As said solvent, the solvent (for example, alcohols, such as ethanol) which can be mixed with water is mentioned. When the aqueous medium is a mixed medium of water and a solvent, the ratio of water to the entire mixed medium is not particularly limited as long as it is within the range that does not hinder the effect of the present invention. From the viewpoint of economic efficiency, for example, It is preferably at least 95% by mass, more preferably at least 98% by mass, and still more preferably substantially 100% by mass. The content of the aqueous medium in the polishing liquid composition of the present invention can be set as particle A1 and component B, as well as the remaining amount of silicon dioxide particles other than particle A1 prepared as needed, and any components described below.

[Acid] The polishing liquid composition of the present invention may contain at least one selected from acids and their salts (hereinafter also referred to as "component C") from the viewpoint of increasing the polishing rate. Component C includes, for example, inorganic acids such as nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, polyphosphoric acid, and amide sulfuric acid; Organic acids such as phosphonic acid, etc. Among them, at least one acid selected from phosphoric acid, sulfuric acid, and 1-hydroxyethylidene-1,1-diphosphonic acid is preferred, and sulfuric acid and At least one acid of phosphoric acid, more preferably phosphoric acid. As a salt of such an acid, the salt of the said acid and at least 1 sort(s) chosen from a metal, ammonia, and an alkylamine is mentioned, for example. Specific examples of the aforementioned metals include metals belonging to Groups 1 to 11 of the periodic table. Among these, salts of the above-mentioned acids and metals belonging to Group 1 or ammonia are preferable from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuations. Component C may be used alone or in combination of two or more.

The content of component C in the polishing liquid composition of the present invention is preferably at least 0.001% by mass, more preferably at least 0.01% by mass, and still more preferably 0.05% by mass, from the viewpoint of ensuring the polishing rate and reducing short-wavelength fluctuations. Above, more preferably at least 0.1% by mass, and from the same viewpoint, preferably at most 5.0% by mass, more preferably at most 4.0% by mass, still more preferably at most 3.0% by mass, still more preferably at most 2.5% by mass %the following. More specifically, the content of component C is preferably from 0.001% by mass to 5.0% by mass, more preferably from 0.01% by mass to 4.0% by mass, still more preferably from 0.05% by mass to 3.0% by mass, and furthermore More preferably, it is 0.1 mass % or more and 2.5 mass % or less.

[Oxidizing agent] The polishing liquid composition of the present invention may contain an oxidizing agent (hereinafter also referred to as "component D") from the viewpoint of securing the polishing rate and reducing short-wavelength fluctuation. As component D, from the same viewpoint, for example, peroxide, permanganic acid or its salt, chromic acid or its salt, peroxyacid or its salt, oxyacid or its salt, nitric acid, sulfuric acid class etc. Among these, preferably at least one selected from hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (III) sulfate and iron (III) ammonium sulfate, the effect of increasing the grinding speed Hydrogen peroxide is more preferable from the viewpoint of metal ions not adhering to the surface of the substrate to be polished and the viewpoint of ease of acquisition. Component D may be used alone or in combination of two or more.

The content of component D in the polishing liquid composition of the present invention is preferably at least 0.01% by mass, more preferably at least 0.05% by mass, and still more preferably at least 0.1% by mass, from the viewpoint of increasing the polishing rate. From the viewpoint of securing the polishing rate and reducing short-wavelength fluctuations, it is preferably at most 4.0% by mass, more preferably at most 2.0% by mass, and still more preferably at most 1.5% by mass. More specifically, the content of component D is preferably from 0.01% by mass to 4.0% by mass, more preferably from 0.05% by mass to 2.0% by mass, still more preferably from 0.1% by mass to 1.5% by mass.

[Other Components] The polishing liquid composition of the present invention may contain other components as needed. Examples of other components include water-soluble polymers other than component B, thickeners, dispersants, rust inhibitors, alkaline substances, polishing rate enhancers, surfactants, and the like. The above-mentioned other components are preferably contained in the polishing liquid composition within the range that does not impair the effect of the present invention, and the content of the above-mentioned other components in the polishing liquid composition is preferably 0% by mass or more, more preferably more than 0% by mass, Furthermore, it is preferably at least 0.1% by mass, more preferably at most 10% by mass, more preferably at most 5% by mass. More specifically, the content of the above-mentioned other components is preferably from 0 mass % to 10 mass %, more preferably from more than 0 mass % to 10 mass %, more preferably from 0.1 mass % to 5 mass %.

[Alumina Abrasive Grains] The polishing liquid composition of the present invention preferably does not substantially contain alumina abrasive grains from the viewpoint of reducing protrusion defects. In this specification, the so-called "substantially not containing alumina abrasive grains" may include not containing alumina particles, not containing alumina particles in an amount that functions as abrasive grains, or not containing alumina particles in one or more embodiments. Contains alumina particles in amounts that can affect grinding results. The specific content of alumina particles is not particularly limited, but is preferably 5% by mass or less, more preferably 2% by mass or less, further preferably 1% by mass or less, and still more preferably substantially 0% by mass.

[pH value] The pH value of the polishing liquid composition of the present invention is preferably at least 0.5, more preferably at least 0.7, still more preferably at least 0.9, and still more preferably from the viewpoint of ensuring the polishing speed and reducing short-wavelength fluctuations It is 1.0 or more, and from the same viewpoint, it is preferably 6.0 or less, more preferably 4.0 or less, still more preferably 3.0 or less, still more preferably 2.5 or less, still more preferably 2.0 or less. The pH can be adjusted using the above-mentioned acid (component C) or a known pH adjuster. The above pH value is the pH value of the polishing liquid composition at 25° C., which can be measured with a pH meter, and is preferably the value after immersing the electrode of the pH meter in the polishing liquid composition for 2 minutes.

[Manufacturing Method of Polishing Liquid Composition] The polishing liquid composition of the present invention can, for example, be prepared by using known methods to prepare particles A1, component B, and an aqueous medium, and optionally silicon dioxide particles other than particle A1, component C, Manufactured with ingredient D and other ingredients. That is, in another aspect, the present invention relates to a method for producing a polishing liquid composition, which includes at least the step of preparing particle A1, component B, and an aqueous medium. In the present invention, "preparation" includes mixing particle A1, component B and an aqueous medium, and optionally silica particles other than particle A1, component C, component D and other components simultaneously or in any order. When the particle A1 contains a plurality of types of non-spherical silica particles, the plurality of types of non-spherical silica particles may be formulated simultaneously or separately. When the particles A2 that can be compounded as the silica particles other than the particles A1 contain plural kinds of spherical silica particles, the plural kinds of spherical silica particles can be compounded simultaneously or separately. The above preparation can be performed using mixers such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill, for example. The preferable formulation amount of each component in the manufacturing method of the silica slurry and the polishing liquid composition can be set to be the same as the preferable content of each component in the above-mentioned polishing liquid composition of the present invention.

The "content of each component in the polishing liquid composition" in the present invention refers to the content of each of the above-mentioned components at the point when the polishing liquid composition is used for polishing. The polishing liquid composition of the present invention can be stored and supplied in a concentrated state within the range of not impairing its storage stability. In this case, it is preferable at the point which can further reduce manufacturing and transportation costs. When the concentrate of the polishing liquid composition of the present invention is used, it can be used after being appropriately diluted with the above-mentioned water if necessary.

[Polishing liquid set] The present invention relates to a polishing liquid set (hereinafter also referred to as "the polishing liquid set of the present invention"), which is a set for manufacturing a polishing liquid composition, which includes particles A1 A silica dispersion in a container containing silica slurry in an aqueous medium. According to the polishing liquid set of the present invention, a polishing liquid composition capable of increasing the polishing speed and reducing short-wavelength fluctuations can be obtained.

As one embodiment of the polishing liquid set of the present invention, for example, the following polishing liquid set (two-liquid type polishing liquid composition) can be mentioned. The silicon dioxide dispersion liquid, and the additive aqueous solution containing component B and optionally component C and component D are mixed at the time of use, and diluted with an aqueous medium if necessary. Silica particles other than particle A1 may be contained in the above-mentioned silica dispersion liquid. The aqueous medium contained in the above-mentioned silica dispersion may be the total amount or a part of the aqueous medium used to prepare the polishing liquid composition. A part of the aqueous medium used to prepare the polishing composition may be contained in the aqueous additive solution. The above-mentioned arbitrary components may be contained in the above-mentioned silica dispersion liquid and the above-mentioned additive aqueous solution, respectively, if necessary.

[Substrate to be polished] The substrate to be polished by the polishing liquid composition of the present invention is a substrate for manufacturing magnetic disk substrates, for example, an aluminum alloy substrate coated with Ni-P is preferred. The term "Ni-P-plated aluminum alloy substrate" in the present invention means that the surface of the aluminum alloy substrate is ground and then subjected to electroless Ni-P plating. A magnetic disk substrate can be manufactured by performing a step of forming a magnetic layer on the surface of the substrate by sputtering after the step of polishing the surface of the substrate to be polished using the polishing liquid composition of the present invention. The shape of the substrate to be polished includes, for example, a shape with a flat surface such as a disc, a plate, a block, or a prism, or a shape with a curved surface such as a lens. The substrate to be polished is preferably a disk. In the case of a disc-shaped substrate to be polished, its outer diameter is, for example, 10-120 mm, and its thickness is, for example, 0.5-2 mm.

Generally, a magnetic disk is manufactured by polishing a substrate to be polished after a grinding step through a rough grinding step and a finish polishing step, and then passing through a magnetic layer forming step. The polishing liquid composition of the present invention is preferably used for grinding in the coarse grinding step.

[Manufacturing method of magnetic disk substrate] The present invention relates to a manufacturing method of a magnetic disk substrate (hereinafter also referred to as "substrate manufacturing method of the present invention"), which includes polishing the substrate to be polished using the polishing liquid composition of the present invention Step (hereinafter also referred to as "polishing step using the polishing liquid composition of the present invention"). The polishing step using the polishing liquid composition of the present invention in the substrate manufacturing method of the present invention is, for example, a rough polishing step.

In the polishing step using the polishing liquid composition of the present invention, for example, the substrate to be polished is clamped by a platen to which a polishing pad is attached, the polishing liquid composition of the present invention is supplied to the polishing surface, and the polishing is moved while applying pressure. Pad or substrate to be polished, whereby the substrate to be polished can be polished.

The polishing load in the polishing step using the polishing liquid composition of the present invention is preferably at least 3 kPa, more preferably at least 5 kPa, and still more preferably at least 7 kPa, from the viewpoint of securing the polishing speed and reducing short-wavelength fluctuations. , and preferably less than 30 kPa, more preferably less than 25 kPa, further preferably less than 20 kPa. More specifically, the grinding load is preferably from 3 kPa to 30 kPa, more preferably from 5 kPa to 25 kPa, still more preferably from 7 kPa to 20 kPa. The so-called "grinding load" in the present invention refers to the pressure of the platen applied to the polished surface of the substrate to be polished during polishing. The adjustment of the grinding load can be carried out by the air pressure applied to the platen or the substrate, or the load of the plumb weight.

In the polishing step using the polishing liquid composition of the present invention, the polishing amount per ¹ cm of the substrate to be polished is preferably 0.20 mg or more, more preferably 0.30 mg or more from the viewpoint of ensuring the polishing speed and reducing short-wavelength fluctuations , more preferably 0.40 mg or more, and from the same viewpoint, preferably 2.50 mg or less, more preferably 2.00 mg or less, still more preferably 1.60 mg or less. More specifically, the polishing amount per 1 cm ² of the substrate to be polished is preferably from 0.20 mg to 2.50 mg, more preferably from 0.30 mg to 2.00 mg, and still more preferably from 0.40 mg to 1.60 mg.

The supply rate of the polishing liquid composition per ¹ cm of the substrate to be polished in the polishing step using the polishing liquid composition of the present invention is preferably 2.5 mL/min or less, more preferably 2.0 mL from the viewpoint of economical efficiency /min or less, and further preferably less than 1.5 mL/min, and, from the viewpoint of increasing the polishing speed, the substrate to be polished is preferably more than 0.01 mL/min per 1 cm ² , more preferably more than 0.03 mL/min, More preferably, it is 0.05 mL/min or more. More specifically, the supply rate of the polishing liquid composition per ¹ cm of the substrate to be polished is preferably more than 0.01 mL/min and less than 2.5 mL/min, more preferably more than 0.03 mL/min and less than 2.0 mL/min, More preferably, it is not less than 0.05 mL/min and not more than 1.5 mL/min.

As a method of supplying the polishing liquid composition of this invention to a grinder, the method of supplying continuously using a pump etc. is mentioned, for example. When supplying the polishing liquid composition to the grinding machine, in addition to the method of supplying it in the form of one liquid containing all the components, it is also possible to consider the storage stability of the polishing liquid composition, etc., and divide it into a plurality of component liquids for preparation, Supplied in the form of more than 2 liquids. In the latter case, the above-mentioned plurality of preparation component liquids are mixed, for example, in a supply pipe or on a substrate to be polished to form the polishing liquid composition of the present invention.

According to the substrate manufacturing method of the present invention, the polishing speed can be increased, and the short-wavelength fluctuation of the substrate surface after polishing can be reduced, so that the effect of efficiently manufacturing a magnetic disk substrate with improved substrate quality can be exerted.

[Grinding method] The present invention relates to a polishing method of a magnetic disk substrate (hereinafter also referred to as the polishing method of the present invention), which includes a polishing step using the polishing liquid composition of the present invention. The polishing step using the polishing liquid composition of the present invention in the polishing method of the present invention is, for example, a rough grinding step.

By using the polishing method of the present invention, the polishing speed can be increased, and the short-wavelength fluctuation of the substrate surface after polishing can be reduced, so the effect of improving the productivity of the magnetic disk substrate with improved substrate quality can be exerted. The specific grinding method and conditions can be set to be the same as the above-mentioned substrate manufacturing method of the present invention. Example

Hereinafter, the present invention will be described in further detail by way of examples, but these are examples, and the present invention is not limited by these examples.

1. Preparation of Polishing Fluid Composition Using the abrasive grains (particles A1 and A2) in Table 1, the water-soluble polymers in Tables 2-4, acid (phosphoric acid), oxidizing agent (hydrogen peroxide), and water, the preparation examples 1-20 and the polishing liquid compositions of Comparative Examples 1-6 (Table 2-4). The content (active ingredient) of each component in the polishing liquid composition is set as follows: abrasive grain: 6% by mass, water-soluble polymer: 0.005-0.5% by mass, phosphoric acid: 2% by mass, hydrogen peroxide: 1% by mass. The pH value of the polishing liquid composition is 1.5. The particles A1 and A2 used for the abrasive grains are colloidal silica particles produced by the water glass method. The pH value was measured at 25° C. using a pH meter (manufactured by Toa DKK Co., Ltd.), and the value obtained after immersing the electrode in the polishing liquid composition for 2 minutes was used.

[Table 1]

In the preparation of the polishing liquid compositions in Tables 2-4, the following water-soluble polymers were used. B1: AA/AMPS copolymer (mass ratio 90/10, weight average molecular weight 8,000, "Aron A6017" manufactured by Toagosei Co., Ltd.) B2: AA/AMPS copolymer (mass ratio 80/20, weight average molecular weight 1,823, Toagosei "Aron A6016" manufactured by the company) B3: AA/AMPS copolymer (mass ratio 50/50, weight average molecular weight 1,710) B4: AA/AMPS copolymer (mass ratio 60/40, weight average molecular weight 10,000, manufactured by Toagosei Co., Ltd. "Aron A6012") B5: AA/AMPS copolymer (mass ratio 40/60, weight average molecular weight 10,000, "Aron A6020" manufactured by Toagosei Co., Ltd.) B6: AA/AMPS copolymer (mass ratio 30/70, weight Average molecular weight 1,330) B7: AA/AMPS copolymer (mass ratio 5/95, weight average molecular weight 1,180) B8: AA/HAPS copolymer (mass ratio 60/40, weight average molecular weight 10,000) B9: Poly AMPS (weight average molecular weight 5,000) (not component B) B10: Styrene/styrene sulfonic acid copolymer (weight average molecular weight 8,000) (not component B) B11: polystyrene sulfonic acid (weight average molecular weight 10,000) (not component B)

2. Measuring method of each parameter (1) Measuring method of the average sphericity of abrasive grains. Use a scanner to observe the grinding with TEM ("JEM-2000FX" manufactured by JEOL Ltd., 80 kV, 10,000-50,000 times) The photos obtained from the particles (particle A1, particle A2) were scanned to a personal computer in the form of image data, and the analysis software (Mitani Corporation "WinROOF (version 3.6)") was used to project 500 silica particles in the following manner The image is parsed. Then, based on the area S and perimeter L of each particle, the sphericity of each particle was calculated by the following formula to obtain the average value of the sphericity (average sphericity). Sphericity=4π×S/L ²

(2) Measuring method of average primary particle diameter of abrasive grains The average primary particle diameter of abrasive grains (particle A1, particle A2) is calculated using the BET specific surface area S (m ² /g) calculated by the BET method, according to the following formula And figured out. Average primary particle size (nm)=2727/S

The BET specific surface area S is after performing the following [pretreatment], and accurately weighs about 0.1 g of the sample to be measured with an accuracy of 4 decimal places (0.1 mg), and puts it in the measuring tank, immediately before the specific surface area is measured. After drying at 110°C for 30 minutes, the specific surface area was measured by the BET method using a specific surface area measuring device (Micromeritics automatic specific surface area measuring device, Flowsorb III2305, manufactured by Shimadzu Corporation). [Pretreatment] Take the slurry-like abrasive grains and place them in a petri dish, and dry them in a hot air dryer at 150°C for 1 hour. The dried sample was pulverized finely with an agate mortar to obtain a measurement sample.

(3) The method of measuring the average secondary particle size of the abrasive grains is prepared by diluting the abrasive grains (particle A1, particle A2) with ion-exchanged water to prepare a dispersion containing 0.02% by mass of the abrasive grains to make a sample, using dynamic light scattering The device (“DLS-7000” manufactured by Otsuka Electronics Co., Ltd.) was used for measurement under the following conditions. The particle size (D50) at which the area of the obtained particle size distribution in conversion of the weight becomes 50% of the whole is taken as the average secondary particle size. <Measurement conditions> Sample volume: 30 mL Laser: He-Ne, 3.0 mW, 633 nm Scattered light detection angle: 90° Accumulation count: 200 times

(4) The method for measuring the weight average molecular weight of water-soluble polymers. Measurement was performed by gel permeation chromatography (GPC) under the following conditions. <Measurement conditions> Detector: Shodex RI SE-61 differential refractive index detector Column: G4000PWXL manufactured by Tosoh Co., Ltd. and G2500PWXL connected in series were used. Eluent: Adjust the concentration to 0.5 g/100 mL with 0.2 M phosphate buffer/acetonitrile=90/10 (volume ratio), and use 20 μL. Column temperature: 40°C Flow rate: 1.0 mL/min Standard polymer: monodisperse polyethylene glycol with known molecular weight

(5) Measurement method of surface tension of water-soluble polymers: pH of 1% by mass aqueous solution of water-soluble polymers (prepared by diluting water-soluble polymers with pure water so that the solid content becomes 1% by mass) Adjusted to 1.5. Phosphoric acid is used for pH adjustment. Then, the pH-adjusted aqueous solution (25° C.) was loaded into a petri dish, and by the Wilhelmy method (a method of dipping a platinum plate and pulling it at a certain speed), a surface tensiometer (manufactured by Kyowa Interface Chemical Co., Ltd. , "CBVP-Z") to measure surface tension. The measurement results are shown in Tables 2-4.

3. Polishing of substrates Using the prepared polishing liquid compositions of Examples 1-20 and Comparative Examples 1-6, the substrates to be polished were polished under the following polishing conditions.

[Grinding conditions] Grinding machine: Double-sided grinding machine (9B type double-sided grinding machine, manufactured by SpeedFam Co., Ltd.) Grinding substrate: Ni-P plated aluminum alloy substrate, thickness 1.27 mm, diameter 95 mm, number of pieces 10 pieces of polishing liquid : Polishing liquid composition Polishing pad: Suede type (foam layer: polyurethane elastomer, thickness: 1.0 mm, average pore diameter: 30 μm, compressibility of surface layer: 2.5%, manufactured by Filwel Corporation) Platen rotation speed: 40 rpm Grinding load: 9.8 kPa (set value) Grinding fluid supply: 60 mL/min Grinding time: 6 minutes

4. Evaluation method (1) Evaluation of polishing speed The polishing speed of the polishing liquid compositions of Examples 1-20 and Comparative Examples 1-6 was evaluated in the following manner. First, the weight of each substrate before and after polishing was measured using a scale (manufactured by Sartorius, "BP-210S"), and the amount of mass loss was calculated from the mass change of each substrate. The value obtained by dividing the average mass loss of all 10 pieces by the polishing time was defined as a polishing rate, and was calculated by the following formula. Mass reduction (g)={mass before grinding (g)-mass after grinding (g)} Grinding speed (mg/min)=Mass reduction (mg)/Grinding time (min) <Evaluation criteria> Grinding speed : Evaluation 18.5 mg/min or more: "A: The polishing rate is excellent, and further improvement in productivity can be expected" 17.5 mg/min or more and less than 18.5 mg/min: "B: The polishing rate is good, and productivity improvement can be expected" Not reached 17.5 mg/min: "C: Reduced productivity"

(2) Evaluation of waviness (short-wavelength waviness) Two boards were arbitrarily selected from among 10 polished substrates, and measured at any three points (12 points in total) on both sides of each selected substrate under the following conditions. The average value of the measured values at these 12 points was calculated as the short-wavelength fluctuation of the substrate. <Measurement conditions> Machine: Zygo NewView5032 Lens: 2.5x Michelson Zoom ratio: 0.5x Removal: Cylinder Filter: FFT (Fast Fourier Transform, Fast Fourier Transform) Fixed Band Pass Fluctuation wavelength: 80~500 μm area: 4.33 mm×5.77 mm <Evaluation criteria> Ripple: Evaluation of less than 1.4 nm: "A: The effect of reducing waviness is excellent, and an improvement in productivity can be expected" More than 1.4 nm and less than 1.7 nm: "B : The reduction effect of fluctuation is good, and it can be actually produced" 1.7 nm or more: "C: Improvement is required for actual production"

5. Results The results of each evaluation are shown in Tables 2-4.

[Table 2]

[table 3]

[Table 4]

As shown in Tables 2 to 4, compared with Comparative Examples 1 to 6, in Examples 1 to 20 containing non-spherical silica particles and specific water-soluble polymers, the polishing speed was increased and short-wavelength fluctuations were reduced. Industrial availability

According to the present invention, the polishing speed can be increased, and the short-wavelength fluctuation after polishing can be reduced, so that the productivity of the manufacture of the magnetic disk substrate can be improved. The present invention can be suitably used in the manufacture of magnetic disk substrates.

Fig. 1 is an example of an electron microscope (TEM) observation photo of special-shaped silica particles.

Claims (17)

A polishing liquid composition, which is a polishing liquid composition for rough grinding of an aluminum alloy substrate plated by Ni-P, which contains non-spherical silicon dioxide particles, a water-soluble polymer and an aqueous medium, and the above-mentioned water-soluble The surface tension of a 1 mass% aqueous solution of the polymer at 25°C and a pH value of 1.5 is not less than 52mN/m and not more than 71mN/m. The polishing liquid composition according to claim 1, wherein the content of the above-mentioned water-soluble polymer is not less than 0.005% by mass and not more than 0.5% by mass. The polishing liquid composition as claimed in claim 1, wherein the above-mentioned water-soluble polymer is a copolymer containing structural units derived from vinyl monomers with carboxylic acid groups and structural units derived from vinyl monomers with sulfonic acid groups . The polishing liquid composition as claimed in claim 3, wherein the mass ratio of the above-mentioned structural units derived from vinyl monomers with carboxylic acid groups to the above-mentioned structural units derived from vinyl monomers with sulfonic acid groups is 50/50 or more And below 90/10. The polishing composition according to claim 3, wherein the above-mentioned water-soluble polymer is selected from at least one of the following copolymers, which contain structural units derived from (meth)acrylic acid or its salts and derived from 2-acrylamide - Copolymers of structural units derived from 2-methylpropanesulfonic acid or its salts, containing structural units derived from (meth)acrylic acid or its salts and derived from 2-hydroxy-3-(allyloxy)propanesulfonic acid Copolymers of structural units derived from (meth)acrylic acid or its salts and structural units derived from vinylsulfonic acid or A copolymer of structural units of its salt. The polishing composition according to claim 3, wherein the above-mentioned water-soluble polymer is selected from at least one of the following copolymers, which contain structural units derived from (meth)acrylic acid or its salts and derived from 2-acrylamide - Copolymers of structural units derived from 2-methylpropanesulfonic acid or its salts, and copolymers containing structural units derived from (meth)acrylic acid or its salts and structural units derived from vinylsulfonic acid or its salts. The polishing liquid composition as claimed in item 3, wherein the above-mentioned water-soluble polymer is at least one selected from the following copolymers, that is, containing structural units derived from acrylic acid and derived from 2-acrylamide-2-methylpropanesulfonate Copolymers of structural units of acid, and copolymers containing structural units derived from acrylic acid and structural units derived from 2-hydroxy-3-(allyloxy)propanesulfonic acid. The polishing composition according to claim 3, wherein the water-soluble polymer is a copolymer containing structural units derived from acrylic acid and structural units derived from 2-acrylamide-2-methylpropanesulfonic acid. The polishing composition according to claim 1, wherein the average sphericity of the non-spherical silica particles is not less than 0.55 and not more than 0.85. The polishing liquid composition according to claim 1, wherein the average secondary particle diameter of the above-mentioned non-spherical silica particles is not less than 50 nm and not more than 500 nm. The polishing composition according to claim 1, wherein the average primary particle size of the non-spherical silica particles is not less than 50 nm and not more than 200 nm. The polishing liquid composition according to any one of claims 1 to 11, further comprising spherical silica particles. Such as the polishing liquid composition of claim 12, wherein the mass ratio of non-spherical silicon dioxide particles to spherical silicon dioxide particles (content of non-spherical silicon dioxide particles/content of spherical silicon dioxide particles) is 5 Above /95 and below 95/5. A method for manufacturing a magnetic disk substrate, which includes a polishing step of using the polishing liquid composition according to any one of claims 1 to 13 to polish a Ni-P plated aluminum alloy substrate. The method for manufacturing a magnetic disk substrate as claimed in claim 14, wherein the grinding step is a rough grinding step. A method for polishing a substrate, comprising a step of polishing a Ni-P plated aluminum alloy substrate using the polishing liquid composition according to any one of claims 1 to 13. The polishing method of a substrate as claimed in claim 16, wherein the above-mentioned polishing step is a rough polishing step.

Images